1. Field of the Invention
The present invention relates to a method of forming a metal fine particle pattern and a method of forming an electroconductive pattern, and particularly relates to a method including the step of forming a thin film or fine particle region of a metal such as silver and copper so as to form a metal fine particle pattern or an electroconductive pattern which is useful for electric wiring materials, electromagnetic wave-blocking films, magnetic films, or the like and has high density and good durability and productivity.
2. Description of the Related Art
Conventionally, a variety of electroconductive pattern materials have been used to form wiring substrates and the like. A typical method of forming such patterns includes the steps of: forming a thin film of an electroconductive material on an insulating material by a known method such as vacuum deposition; subjecting it to a resist process; performing pattern exposure to remove part of the previously formed resist; and then performing etching to form the desired pattern. Such a method of forming patterns requires at least four steps. If wet etching is further performed, the step of treating its waste liquid will be required. Thus, the conventional method has to use a complicated process.
There is another known method which uses a photoresist to form an electroconductive pattern material. This method includes the steps of providing a substrate having a photoresist polymer coating or having a photoresist attached on a dry film and exposing the substrate to UV light through a certain photomask so that a pattern such as a grid pattern is formed. For example, such a method is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2001-53488. Such a method is useful in forming an electromagnetic wave shield which is required to have high electroconductivity.
In recent years, as micromachines and a smaller version of VLSI have been developed, their wiring structure has been required to be as small as nano-metric scale. However, the conventional metal etching has a limit to how fine a structure it can produce, and a small wiring part can break when worked.
Attention is focused not only on such a continuous thin metal film but also on a metal fine particle pattern which is formed by selective adsorption of metal fine particles onto a specific region.
In recent years, as an advanced information society has been developed, there have been remarkable advances in electronic instruments. Particularly, the advances in computer technology, which support the development of the advanced information society, significantly contribute to the production of high recording density magnetic disks as well as to the production of high-density semiconductor LSI. In the production of high recording density magnetic disks, there has been a demand for a defect reduction to a minimum and a demand for high flatness, with respect to the magnetic medium layer. For these purposes, a film is currently used which comprises metal fine particles with magnetic properties dispersed on the surface of a substrate. In addition, JP-A No. 2001-110050 discloses that if such metal fine particles are arranged in a pattern, the recording capacity can be increased. Thus, forming a metal fine particle adsorption region in a pattern has become more important. However, such a known method of forming a metal fine particle pattern, which can immediately lead to an improvement in recording density, also has a problem similar to that with the method of forming the thin metal film pattern. Thus, it has also been difficult to form a metal fine particle pattern of very small size at high resolution.